No screenshot possible with v2.0.3

Hi, I’m using CMS 2.0.3 (docker/ubuntu) with Android client 201-54369af. All works (showing layouts, xmr, logged in, screenshot?) but no screenshot thumbnail is shown. In the logs are no errors. The shared/cms/library/screenshots-Folder is empty.

Can you please give me advice.

Thank you.

Best regards
Thomas